氧化镧和硬脂酸镧对LLDPE结晶与力学性能的影响

采用DSC研究了稀土化合物氧化镧、硬脂酸镧对LLDPE(线性低密度聚乙烯)非等温结晶行为的影响。随着氧化镧和硬脂酸镧浓度的增加,LLDPE的结晶度出现下降的趋势。氧化镧可起到异相成核的作用,使LLDPE的结晶速率增快,冷却结晶峰向高温移动,而硬脂酸镧没有改变结晶峰的位置,对结晶速率没有影响。广角XRD(X射线衍射)结果显示氧化镧和硬脂酸镧没有使LLDPE的晶型产生变化,但在有氧化镧的体系中,LLDPE在110和200晶面的晶粒尺寸有明显增大。力学实验显示,氧化镧使LLDPE的拉伸强度略有降低,断裂伸长率则有较大幅度的下降。硬脂酸镧对LLDPE的拉伸强度影响不大。却使断裂伸长率有大幅度提高。

Effects of La2O3 and Lanthanum Stearate on Crystallization and Mechanical Properties of LLDPE

The crystallization and mechanical properties of LLDPE and its blends with La_2O_3 and lantha- num stearate were studied with DSC,wide angle X-ray and tensile measurement.The crystallization rate of LLDPE could be increased by the heterogeneous nucleation effect of La_2O_3 while the same phenomenon didn't occur in the case of lanthanum stearate.The crystallinity declined in both blends of LLDPE with La_2O_3 and lanthanum stearate when the concentration of fillers increased.Wide angle X-ray results show no new crystalline form appeared in the composites,but the crystallite dimensions in 110 and 200 reflections increased in the case of La_2O_3.The tensile strength of LLDPE decreased slightly and the elongation to break decreased distinctly with the addition of La_2O_3,while in the case of lanthanum stearate,the tensile strength remained almost the same but the elongation to break improved remarkably.